Conventional boats with inboard internal combustion engines have their engines located within a closed engine compartment in order to separate the boat passengers from the noise and noxious fumes of the engine. Substantial problems may arise from the location of the engine within a closed compartment in view of the possible accumulation of combustible vapors within the compartment. Unless these accumulated combustible vapors are exhausted from the compartment, an explosion may occur upon engine start-up, potentially causing severe damage and personal injury.
While combustible vapor detectors 1 are known in the art, such detectors merely provide an indication as to whether a substantial accumulation of detectable vapors exists in the engine compartment. Even if the detector is working properly, an inattentive operator may still attempt to start the engine, regardless of any accumulation of combustible vapors.
Another problem with conventional vapor detectors is the short life span of many components within the detector due to the marine environment. Oxidation and other environmental factors dramatically shorten the life of the sensitive electrical components of a detector. Previous attempts to overcome these problems have relied on electrical circuits tied into an exhaust vent in the engine compartment which prevent starting of the engine unless the exhaust fan has been activated. In some cases, a time delay circuit is utilized to permit a predetermined amount of venting of the engine compartment before the starting circuit may be energized. The main problem with such devices is that the circuits rely on activation of a vent fan, rather than actual venting of the engine compartment. In the event that the passageway venting fumes from the engine compartment becomes blocked, the fan may still be energized and the engine started regardless of the fact that fumes have not actually been vented.
It is therefore a general object of the present invention to provide an improved fume exhaustion safety device.
Another object of the present invention is to provide a fume exhaustion safety device which is controlled by the physical movement of fumes from the engine compartment.
Another object is to provide a fume exhaustion safety device which is resistant to the elements of a marine environment, so as to provide for a long life.
A further object of the present invention is to provide a fume exhaustion safety device which prevents start-up of an engine prior to actual physical exhaustion of fumes from the engine compartment.
Still another object is to provide a fume exhaustion safety device which is simple to operate and economical to manufacture.
These and other objects will be apparent to those skilled in the art.